Embodiments of the disclosed technology relate to a thin film transistor (TFT), an array substrate and a preparation method thereof.
Presently, since active matrix organic light-emitting displays (AMOLEDs) and low temperature poly-silicon thin film transistor liquid crystal displays (LTPS TFT-LCDs) have advantages of high definition of image, short response time for moving images, lower power consumption, wide viewing angles and ultra-light and thin profiles, they may be among the best choices of display technology in future. However, an a-Si (amorphous silicon) thin film transistor (TFT) commonly used at present in the LCD industry has relatively low mobility, serious threshold voltage drift and bad stability, which renders a-Si TFTs difficult to be applied to a current-driving AMOLED.
Microcrystalline silicon is characterized in good stability, high uniformity of back plate and low process costs and therefore adapted to a display panel, such as an AMOLED, an LTPS TFT-LCD or the like of a big size. However, when a plasma enhanced chemical vapor deposition (PECVD) process is used to prepare an active layer in a thin film transistor, an incubation layer appears in the channel region of an active layer in its lower portion, which is the grown microcrystalline silicon material. This incubation layer results in a number of crystal boundaries and defects in the channel region of the active layer, which decreases the mobility of carriers and causes the response delay of a thin film transistor, low on/off response speed and instability of operating state.